A macrophage chemokinetic factor (CKF) which acts selectively on activated tumoricidal macrophages to increase their rate of migration, is present on the cell membranes and in the culture media of each of the murine tumor cell lines we have tested. This factor is a trypsin sensitive, high molecular weight (300,000-480,000 Mr) material which dissociated to less than 100,000 Mr in the presence of 4M urea. We will initially prepare monoclonal antibodies versus CKF and perform immunofluorescent, flow cytometry, and Western blot studies to characterize the location and size of the CKF from other murine and human neoplastic cell lines. Studies on the biochemical characterization of the low molecular weight CKF will be continued. Experiments will be conducted to determine various factors which influence CKF presentation by neoplastic cells. These include using: (1) synchronous cell cultures to evaluate fluctuations in membrane CKF during the stages of the cell cycle; (2) various metabolic poisons to determine the route of CKF synthesis; (3) enzymes to determine the susceptibility of CKF to proteolysis; and (4) pulse-radio-labeling of amino acids to determine the production time and turnover rate of CKF. Studies will also be initiated to determine the influence of CKF on activated macrophage binding and killing of tumor cells. Finally, using the anti-CKF antibody with flow cytometry, the uptake of CKF by activated, stimulated, and normal macrophages will be quantitated. Fulfillment of these specific aims will provide basic knowledge of the biochemical and metabolic nature of the CKF and an initial examination of its role in macrophage-tumor cell interactions. Future studies would more thoroughly define the role of the CKF in the host response to cancer and, if indicated, an attempt to modulate the CKF levels to enhance elimination of neoplastic cells, or use the anti-CKF antibodies to detect and possibly eliminate neoplastic cells in vivo. (HF)